In all browsers the player shows, but in Firefox the video doesn't load. My log shows the "loading video" message on firefox, but nothing else happens after that. Not even an error. If I try to call ytplayer.loadVideoById('jc8n44ddy9A', 0); manually after everything is loaded, I get the error ReferenceError: ytplayer is not defined.

I realize that ytplayer isn't explicitly defined as a variable by me, but my guess(?) is that the YouTube API does that because it works in the other browsers. Also if I defined just var ytplayer globally somewhere it doesn't fix it.